The facility with which he had learned Chinese, and the success which his proficiency commanded, naturally inclined less gifted scholars to resent the impatience with which he regarded their mistakes, and at different times bitter controversies arose between Julien and his fellow sinologues on the one subject which they had in common. In 1842 appeared from his busy pen a translation of the _Tao te King_, the celebrated work in which Lao-tsze attempted to explain his idea of the relation existing between the universe and something which he called _Tao_, and on which the religion of Taoism is based. From Taoism to Buddhism was a natural transition, and about this time Julien turned his attention to the Buddhist literature of China, and more especially to the travels of Buddhist pilgrims to India. In order that he might better understand the references to Indian institutions, and the transcriptions in Chinese of Sanskrit words and proper names, he began the study of Sanskrit, and in 1853 brought out his _Voyages du pélérin Hiouen-tsang_, which is regarded by some critics as his most valuable work. Six years later he published _Les Avadânas, contes et apologues Indiens inconnus jusqu'à ce jour, suivis de poésies et de nouvelles chinoises_. For the benefit of future students he disclosed his system of deciphering Sanskrit words occurring in Chinese books in his _Méthode pour déchiffrer et transcrire les noms sanscrits qui se rencontrent dans les livres chinois_ (1861). This work, which contains much of interest and importance, falls short of the value which its author was accustomed to attach to it. It had escaped his observation that, since the translations of Sanskrit works into Chinese were undertaken in different parts of the empire, the same Sanskrit words were of necessity differently represented in Chinese characters in accordance with the dialectical variations. No hard and fast rule can therefore possibly be laid down for the decipherment of Chinese transcriptions of Sanskrit words, and the effect of this impossibility was felt though not recognized by Julien, who in order to make good his rule was occasionally obliged to suppose that wrong characters had by mistake been introduced into the texts. His Indian studies led to a controversy with Joseph Toussaint Reinaud, which was certainly not free from the gall of bitterness. Among the many subjects to which he turned his attention were the native industries of China, and his work on the _Histoire et fabrication de la porcelaine chinoise_ is likely to remain a standard work on the subject. In another volume he also published an account of the _Industries anciennes et modernes de l'empire chinois_ (1869), translated from native authorities. In the intervals of more serious undertakings he translated the _San tseu King_ (_Le Livre des trois mots_); _Thsien tseu wen_ (_Le Livre de mille mots_); _Les Deux cousines_; _Nouvelles chinoises_; the _Ping chan ling